Hormones are known to control the metabolic processes both in growing and mature organisms. Peptides often act as hormones. They are not only hormonally active themselves but regulate the action of other hormones, which control the vital activity of the organism. However, the potential of such natural compounds is limited. Therefore, many scientific laboratories have tried to develop methods for preparing synthetic derivatives of natural peptides, which are more active than their natural analogues (EP 0136720, 1984; EP 0137904, 1984). Moreover, new peptides have been synthesized, which are absent in the organism but have unique properties. Among them there is a special group of physiologically active peptides directly or indirectly controlling the action of hormones such as the growth hormone. Some of these active peptides increase the growth hormone level in blood (PCT 89/07111, 1989; PCT 91/16923, 1991) while others suppress the hormone (FR 2235701, 1978; FR 2532308, 1982).
A peptide which activates the growth of the epidermal layer in man (PCT 90/13570, 1990), and a metal-containing peptide, which has a significant stimulating effect on hair growth in warm-blooded animals (PCT 91/07431, 1991) have been synthesized. Another peptide analogue has been reported to facilitate hair removal in animals (FR 2487677, 1982).
Different peptide compositions evidently make it possible to control metabolic processes. The most promising task is, however, the development of compounds and preparations with many-sided actions.
At present, there are only a few peptides with comprehensive actions, for instance, the analogue of the P substance described in U.S. Pat. No. 4,680,283. The peptide synthesized as described in the patent has a range of useful properties. Its acts as a biostimulator, and has an analgesic effect similar to that of morphine.
Many studies have shown the importance of synthesizing peptides with opiate-like properties. Unfortunately, the production of morphine-like compounds from natural sources is limited by the complexity of the manufacturing processes (U.S. Pat. No. 4,042,682, 1977). This circumstance resulted in the creation of an arsenal of synthetic analogues (U.S. Pat. No. 4,681,871, 1987; EP 0112036, 1983; EP 0221019, 1986).
Some opiate-like peptides have become known and clinically used in the treatment of brain ischemia (DE 3447720, 1985; U.S. Pat. No. 4,684,624, 1987), for pain relief in pregnant women (EP 0099173, 1984), and only as analgesics. They are reported to be especially effective when used in combination with conventional drug therapy in many diseases (EP 096592, 1983; EP 0099286, 1984; U.S. Pat. No. 4,123,523, 1987).
However, the known synthetic peptides cannot completely satisfy all medical requirements, since they do not have the necessary combination of properties, which would increase their effectiveness. Furthermore, many of them are effective only in large doses that can cause side effects.